The present invention relates generally to fuel system assemblies for use on vehicles.
Vehicles that use diesel engines to operate create a concern with flow of the diesel fuel during cold weather conditions. This flow concern can make starting and operating the engine more difficult in these cold conditions. In addition, diesel engines may utilize fuel as a coolant, lubricant and actuation fluid, where the heated fuel is returned to the bulk fuel tank to be cooled. The performance of the cooling strategy is dependent upon the ability to minimize the temperature of the fuel delivered to the engine and so is dependent upon the ability to separate returning hot fuel from delivered cool fuel.
Attempting to overcome the concern with cold diesel fuel, thermally controlled valves have been employed that direct return fuel directly to the fuel filter inlet (only) from the return fuel line. This system, however, requires a low fuel feed pressure to operate properly, i.e., the fuel feed pressure must be less than the return fuel pressure. This limits the applicability and effectiveness of such a system.